A South San Francisco child enjoyed bath time at his home because of the colorful orange and red water. The water did not have this rusty color at its source, and the water department could not culture the Acidithiobacillus bacteria responsible for the rusty color from the source. How were the bacteria getting into the household water? What bacterial structures make this possible?

It oxidies iron and inorganic sulfur compounds. The oxidation process can be harmful, as it produces sulfuric acid, which is a major pollutant. It has been suggested that T. ferrooxidans forms a symbiotic relationship with members of the genus Acidiphilium, a bacterial capable of iron reduction. Other species of Thiobacillus grow in water and sediment; there are both freshwater and marine strains.

The bacteria are usually found in rivers, canals, mine drainage effluents and mining areas. So there may be some source of these bacilli near their house. They require inorganic sources to grow and contain an enzyme called ferrous oxidase that allows them to metabolize iron.

They eat iron pipes corroding the pipes leading into households and produce a thick slime layer biofilm.